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# C3 remainder theorem

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1. divide x³+x²-7 by x-3

help pls
2. (Original post by Big white)
divide x³+x²-7 by x-3

help pls
Do you know how to do long division?
3. (Original post by Zacken)
Do you know how to do long division?
yes and i can do that but the question states i must use remainder theorem
4. (Original post by Big white)
yes and i can do that but the question states i must use remainder theorem
Pretty sure they're all the same thing?
5. (Original post by Zacken)
Pretty sure they're all the same thing?
here what are they doing at the bit where they say compare coefficients because i don't understand what they've done
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6. (Original post by Big white)
here what are they doing at the bit where they say compare coefficients because i don't understand what they've done
They're comparing coefficients.

So the coefficient of x^3 on the LHS is the same as the coefficient of x^3 on the RHS, etc...
7. (Original post by Zacken)
They're comparing coefficients.

So the coefficient of x^3 on the LHS is the same as the coefficient of x^3 on the RHS, etc...
but why A=1? why not any other number?
8. (Original post by Big white)
but why A=1? why not any other number?

The coefficient of x^3 on the LHS (left hand site of the equality) is 1. x^3 = 1 * x^3. The coefficient is one, it's 1.

The coefficient of x^3 on the RHS (right hand side of the equality) is A.

The coefficients of x^3 on both sides has to be the same.

So A and 1 have to be the same, this is abbreviated to A = 1.
9. (Original post by Zacken)

The coefficient of x^3 on the LHS (left hand site of the equality) is 1. x^3 = 1 * x^3. The coefficient is one, it's 1.

The coefficient of x^3 on the RHS (right hand side of the equality) is A.

The coefficients of x^3 on both sides has to be the same.

So A and 1 have to be the same, this is abbreviated to A = 1.
Ohhhhhhhhh right i see. but you can only do that for the x³ coefficient?
10. (Original post by Big white)
Ohhhhhhhhh right i see. but you can only do that for the x³ coefficient?
No, you can do that for the x^2 coefficient and of the x^1 coefficient, and for the x^(35345345345345) coefficient.
11. (Original post by Zacken)
No, you can do that for the x^2 coefficient and of the x^1 coefficient, and for the x^(35345345345345) coefficient.
ok so i understand now thanks
12. (Original post by Big white)
ok so i understand now thanks
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